This invention relates generally to an active device used for an active nature to display and a printer engine of a printer, an active matrix display and method of joining the active matrix display.
A prior art active device is described in SID (Society for Information Display) Symposium Digest of Technical Papers, Vol. XVII, pages 296-97 (1986) and is shown in FIG. 1 generally as 101. Liquid crystal display panel 101 includes a lower substrate 102 having a thin film transistor 103 thereon with a pixel or display electrode 104 connected thereto. An upper opposed glass substrate 106 has a transparent electrode 107 deposited thereon and a liquid crystal 108 is disposed between substrates 102 and 106. Thin film transistor 103 is formed by depositing a gate electrode 109 on substrate 102, forming a gate insulation film 111 across substrate 102, depositing an amorphous Si channel region 112 and forming a source region 113 and a drain region 114 in the region above gate electrode 109. A source electrode 116 and a drain electrode 117 are formed and coupled to source region 113 and drain region 114 respectively and drain electrode 117 is coupled t electrode 104.
Conventional liquid crystal display panel 101 has several disadvantages. Pixel information that is a data electric voltage applied to source electrode 116 is transmitted to liquid crystal material 108 between pixel electrode 104 and opposed electrode 107 through amorphous Si channel region 112 which is turned on and off by gate electrode 109. Thus, a data electric voltage is held by a charged amount of liquid crystal material 108. However, the charge in liquid crystal material 108 is reduced as time passes due to leakage of current through thin film transistor 103. In other words, the data electric voltage is lost as time passes. Thus, a clear picture image with sharp contrast is difficult to obtain.
It is also difficult to produce an active device having uniform properties over a large area substrate due to difficulties in the complex manufacturing process. Additionally, the conventional active matrix devices have a complex construction which requires a difficult and long manufacturing process. This results in low yield of devices at high cost. An active matrix display including such active elements encounter the same difficulties in manufacture and loss of contrast.
Accordingly, it is desirable to provide an improved active device, an active matrix display including the improved active devices and a driving method for driving the active matrix display which eliminates these problems associated with prior art devices and provides a clear picture image with sharp contrast at low cost.